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.\" Copyright (c) 1996 Doug Rabson
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.Dd October 17, 2025
.Dt VOP_OPEN 9
.Os
.Sh NAME
.Nm VOP_OPEN ,
.Nm VOP_CLOSE
.Nd open or close a file
.Sh SYNOPSIS
.In sys/param.h
.In sys/vnode.h
.Ft int
.Fn VOP_OPEN "struct vnode *vp" "int mode" "struct ucred *cred" "struct thread *td" "struct file *fp"
.Ft int
.Fn VOP_CLOSE "struct vnode *vp" "int mode" "struct ucred *cred" "struct thread *td"
.Sh DESCRIPTION
The
.Fn VOP_OPEN
entry point is called before a file is accessed by a process and the
.Fn VOP_CLOSE
entry point is called after a file is finished with by the process.
.Pp
The arguments are:
.Bl -tag -width mode
.It Fa vp
The vnode of the file.
.It Fa mode
The access mode required by the calling process.
.It Fa cred
The caller's credentials.
.It Fa td
The thread which is accessing the file.
.It Fa fp
The file being opened.
.El
.Pp
Pointer to the file
.Fa fp
is useful for file systems which require such information, e.g.,
.Xr fdescfs 5 .
Use
.Ql NULL
as
.Fa fp
argument to
.Fn VOP_OPEN
for in-kernel opens.
.Pp
The access mode is a set of flags, including
.Dv FREAD ,
.Dv FWRITE ,
.Dv O_NONBLOCK ,
.Dv O_APPEND .
.Pp
The thread
.Fa td
passed to
.Fn VOP_CLOSE
may be
.Ql NULL
if the last reference to the open file is released from a kernel context, e.g.,
the destruction of a socket buffer containing the file reference in a
.Dv SCM_RIGHTS
message.
.Sh LOCKS
.Fn VOP_OPEN
expects
.Fa vp
to be locked on entry and will leave it locked on return.
.Pp
.Fn VOP_CLOSE
expects at least a reference to be associated with the vnode and does not
care whether the vnode is locked or not.
The lock and reference state is left unchanged on return.
Note that
.Fa vn_close
expects an unlocked, referenced vnode and will dereference the vnode prior
to returning.
.Sh RETURN VALUES
Zero is returned on success, otherwise an error code is returned.
.Sh SEE ALSO
.Xr vnode 9 ,
.Xr VOP_LOOKUP 9
.Sh AUTHORS
This manual page was written by
.An Doug Rabson .
